Hepatoblastomas with carcinoma features represent a biological spectrum of aggressive neoplasms in children and young adults
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ABSTRACT: We molecularly characterized a class of histologically aggressive childhood liver cancers and showed that these tumors are clinically aggressive and that their observed histological features are associated with underlying recurrent molecular features. We proposed a diagnostic algorithm to identify these cancers using a combination of histological and molecular features, and our analysis suggested that these cancers may benefit from specialized treatment strategies that may differ from treatment guidelines for hepatoblastomas and hepatocellular carcinomas.
Project description:We molecularly characterized a class of histologically aggressive childhood liver cancers and showed that these tumors are clinically aggressive and that their observed histological features are associated with underlying recurrent molecular features. We proposed a diagnostic algorithm to identify these cancers using a combination of histological and molecular features, and our analysis suggested that these cancers may benefit from specialized treatment strategies that may differ from treatment guidelines for hepatoblastomas and hepatocellular carcinomas.
Project description:Background & aimsHepatoblastoma (HB) and hepatocellular carcinoma (HCC) are the predominant liver cancers in children, though their respective treatment options and associated outcomes differ dramatically. Risk stratification using a combination of clinical, histological, and molecular parameters can improve treatment selection, but it is particularly challenging for tumors with mixed histological features, including those in the recently created hepatocellular neoplasm not otherwise specified (HCN NOS) provisional category. We aimed to perform the first molecular characterization of clinically annotated cases of HCN NOS.MethodsWe tested whether these histological features are associated with genetic alterations, cancer gene dysregulation, and outcomes. Namely, we compared the molecular features of HCN NOS, including copy number alterations, mutations, and gene expression profiles, with those in other pediatric hepatocellular neoplasms, including HBs and HCCs, as well as HBs demonstrating focal atypia or pleomorphism (HB FPAs), and HBs diagnosed in older children (>8).ResultsMolecular profiles of HCN NOS and HB FPAs revealed common underlying biological features that were previously observed in HCCs. Consequently, we designated these tumor types collectively as HBs with HCC features (HBCs). These tumors were associated with high mutation rates (∼3 somatic mutations/Mb) and were enriched with mutations and alterations in key cancer genes and pathways. In addition, recurrent large-scale chromosomal gains, including gains of chromosomal arms 2q (80%), 6p (70%), and 20p (70%), were observed. Overall, HBCs were associated with poor clinical outcomes.ConclusionsOur study indicates that histological features seen in HBCs are associated with combined molecular features of HB and HCC, that HBCs are associated with poor outcomes irrespective of patient age, and that transplanted patients are more likely to have good outcomes than those treated with chemotherapy and surgery alone. These findings highlight the importance of molecular testing and early therapeutic intervention for aggressive childhood hepatocellular neoplasms.Lay summaryWe molecularly characterized a class of histologically aggressive childhood liver cancers and showed that these tumors are clinically aggressive and that their observed histological features are associated with underlying recurrent molecular features. We proposed a diagnostic algorithm to identify these cancers using a combination of histological and molecular features, and our analysis suggested that these cancers may benefit from specialized treatment strategies that may differ from treatment guidelines for other childhood liver cancers.
Project description:Hepatoblastomas carry few genetic alterations, and we hypothesize that epigenetic changes could be relevant to their onset. DNA methylation profile of hepatoblastomas was explored in relation to liver development using the HM450K platform. Seven paired samples of hepatoblastomas and adjacent non-tumoral livers were studied, with biologicaland results validation validated in an independent group (12 hepatoblastomas) that confirmed 1,359 differentiated methylated CpG sites (DMSs) in hepatoblastomas compared to controls, associated with 979 genes. Hepatoblastomas also exhibited a global low-level hypomethylation when compared with differentiated livers, especially at non-repetitive intergenic DNA (~55% of the hypomethylated CpGs); conversely, most of the hypermethylated CpGs were located in CpG islands. Functional analyses revealed an enrichment in signaling pathways involved in metabolism, negative regulation of cell differentiation, liver development, cancer, and the WNT pathway. Strikingly, an important overlap was observed between hepatoblastomas DMSs and the CpG sites reported to exhibit methylation changes through liver development. Genes with differential methylation were related to maintenance of undifferentiated cell state, cell transformation and tumor progression, and the methylation profile of tumors resembled that of fetal livers. Altogether, our results suggest an arrest at early stages of liver cell differentiation, in line with the hypothesis that hepatoblastoma ontogeny involves the disruption of liver development.
Project description:We report the application of the RNA sequencing technology for profiling gene expression alterations in hepatoblastomas. Comparing 14 hepatoblastomas to a group of control liver samples, a set of 1492 differentially expressed genes (DEGs) was detected, both coding and non-coding. We describe the enrichment of specific biological processes related to up- and downregulated genes, and the disruption of metabolic pathways including lipids, amines, and nicotinamides. Finally, we disclose a robust ncRNA transcriptome perturbation, highlighting a new epigenetic player in the control of gene expression in hepatoblastomas.